This invention relates to an apparatus for evening (levelling) the fiber lap fed to a textile fiber processing machine such as a card, a roller card unit or the like, having a licker-in, a feed roller arranged upstream of the licker-in as viewed in the direction of material feed and a feed table cooperating with the feed roller. The levelling apparatus includes a measuring member for sensing the thickness of the fiber material drawn into the fiber processing machine and a control device which receives signals from the measuring member and which is connected with the drive motor for the feed roller for regulating the rpm of the latter as a function of the sensed thicknesses.
In an apparatus of the above-outlined type, as disclosed, for example, in French Pat. No. 2,322,942, underneath the stationarily supported feed roller there is provided a stationary support on which a plurality of sensor levers (feed table) are movably held. One end of each sensor lever is in the immediate vicinity of the licker-in and is spring-biased against the feed roller. The other end of each sensor lever is coupled to a measuring device which senses and integrates the displacements of the sensor levers as they move dependent upon the thickness of the fiber material which passes through.
It is a disadvantage of the above-outlined arrangement that as the fiber material is being taken over from the feed roller by the licker-in, the working forces (tearing forces) of the licker-in have an effect on each sensor lever and consequently, the measuring results may be distorted. It is a further disadvantage of such a prior art arrangement that the location of measurement in the nipping zone (clamping zone) between the feed roller and the sensor lever extends over a relatively long region (from the beginning of the nipping zone to the end of the sensor lever) in which the feed roller is essentially facing the sensor lever and, as a result, the measuring location is not unequivocally determined. In this arrangement the feed table is formed of a great number of spring-biased sensor levers which are coupled to a "piano key" system which is structurally very complex.